CVD reactors of the prior art, such as metalorganic chemical vapor deposition (MOCVD) reactors, have typically used reservoirs of previously prepared organometallic compounds as sources for reactants. As is well known, these compounds may be extremely toxic and pyrophoric and, in general, are different to handle and store. The volatility, reactiveness, and the tendency of these compounds to readily decompose when exposed to air and moisture has presented a formidable problem. In addition, a complex array of process piping and valves is typically required to deliver the needed quantities of reactants to the MOCVD reactor. Also, separate temperature controls are generally required for each such source of reactants.
MOCVD systems are used, typically, for the deposition of type III-IV and II-VI semiconductors, as well as ceramics, metals and metal alloys. The volatile organometallic source compounds in these MOCVD systems are typically prepared as a gas or a high vapor pressure liquid which is stored in a reservoir. A carrier gas such as hydrogen is "bubbled" through the reservoir and the source compund and the carrier gas are subsequently introduced by means of metered valves into the reactor, or deposition, chamber. Within the chamber the volatile compound or compounds are decomposed and the desired material is deposited therein. The delivery of a known or reproducible amount of reactant to the deposition chamber requires independent temperature and carrier gas flow control mechanisms for each type of required reactant.
As can be appreciated from the foregoing, the required storage of relatively large quantities of these highly toxic and unstable organometallic source compounds has presented a serious problem. In addition, the implementation of the complex piping and process control mechanisms required to introduce desired amounts of these organometallics into the MOCVD reactor has also presented a serious problem.
One further disadvantage of these systems of the prior art is that the use of liquid reservoirs of source compunds in conjunction with a carrier gas "bubbler" is inappropriate in a zero gravity environment such as is found in a spacecraft. Thus, the use of such prior art CVD systems to produce, for example, high-quality semiconductor devices in an orbiting production facility is foreclosed by the reliance of such systems of the prior art on gravitational force for proper operation.